Vane Pump

ABSTRACT

After a vane  4  passes an oil supply groove  13  formed in a housing  2  due to rotation of a rotor  3 , a branch passage  12   a  of an oil supply passage formed in a shank  3 B of the rotor communicates with the oil supply groove  13 , then a lubricating oil flows into a pump room  2 A through the oil supply groove  13.    
     Then, owing to a differential pressure between a first space A and a second space B, the lubricating oil which flowed into the first space is spouted in the direction opposite to the rotational direction, being blown against the vane which subsequently passes, thereby sealing a gap between the vane and the pump room can be rapidly carried out. 
     Even if the lubricating oil is not sufficiently fed into the pump room, a vane pump can rapidly exert its original performance.

TECHNICAL FIELD

The present invention relates to a vane pump, and in particular to avane pump adapted to intermittently feed a lubricating oil to a pumproom owing to rotation of a rotor.

BACKGROUND ART

Conventionally, there is known a vane pump including: a housing having apump room in which an approximately circular, inner wall is formed; arotor rotating at an eccentric position relative to the center of thepump room and sliding in contact with a part of the inner wall of thepump room; and a vane rotated by the rotor, for dividing the pump roominto a plurality of spaces full-time (Patent Document 1).

Then, there is known a vane pump that, in the rotor and the housingdescribed above, an oil supply passage intermittently communicating witha pump room owing to rotation of the rotor is formed, a lubricating oilis intermittently fed through a communicating hole of the oil supplypassage formed in the pump room, and the communicating hole is formed ata position on the side of an intake passage from a center line drawnbetween the center of the pump room and the center of rotation of therotor in the housing.

Patent Document 1: Japanese Patent No. 3107906 (especially FIG. 3)

DISCLOSURE OF THE INVENTION Issues to be Solved by the Invention

Here, the lubricating oil has, in addition to an effect of lubricatingthe vane and the pump room, an effect of sealing a gap between the vaneand the pump room to maintain airtight of a space divided by the vane,and when the lubricating oil is not sufficiently fed into the pump room,such as at the time of engine start, this sealing is not fully effected.

In the case of a conventional vane pump, because the communicating holeis formed at a position on the side of the intake passage from thecenter line, even if the vane passes the communicating hole, a pressurein the space divided by the vane becomes negative, thereby thelubricating oil is made to flow into the pump room only in a manner thatthe lubricating oil is dragged to the rotational direction of the vane.

Therefore, it takes a considerable time until the lubricating oil is fedbetween the vane and the pump room, and sealing the gap between the vaneand the pump room is fully effected, and there arose a problem that,during this time period, the vane pump cannot fulfill its originalperformance.

In view of such a problem, an object of the present invention is toprovide a vane pump which can rapidly exert its original performance,even when an amount of the lubricating oil fed to a pump room is small,such as at the time of engine start.

Means to Solve the Issues

Therefore, the vane pump according to the present invention is a vanepump including: a housing having a pump room in which an approximatelycircular, inner wall is formed; a rotor rotating at an eccentricposition relative to the center of the pump room and sliding in contactwith a part of the inner wall of the pump room; and a vane rotated bythe rotor, for dividing the pump room into a plurality of spacesfull-time, wherein

in the housing, among spaces divided by a center line drawn between thecenter of the pump room and the center of rotation of the rotor, anintake passage in one space and an exhaust passage in the other spaceare formed, respectively,

further, in the rotor and the housing, an oil supply passageintermittently communicating with the pump room owing to rotation of therotor is formed, and

a lubricating oil is intermittently fed through a communicating hole ofthe oil supply passage formed in the pump room, characterized in that

the communicating hole is formed in a space on the side of the exhaustpassage from the center line in the pump room, and

the vane passes the communicating hole, at the same time, the oil supplypassage and the pump room are adapted to communicate with each other.

EFFECT OF THE INVENTION

According to the present invention, when the vane passes the exhaustpassage, the pump room is divided into three spaces by the vane, andamong them, the space on the side where the rotor contacts with the pumproom is divided into a space on the side of the intake passage and aspace on the side of the exhaust passage relative to the center line bythe rotor.

At this time, a pressure in the space on the side, where the rotorcontacts with the pump room, of the intake passage from the center lineis made negative due to suction of a gas through the intake passage, anda pressure in the space on the side where the rotor does not contactwith the pump room is made negative, because its volume is increased byrotation of the vane.

Further, the space on the side, where the rotor contacts with the pumproom, of the exhaust passage from the center line has a higher pressurethan the space in which the pressure is negative due to an increase ofthe volume as described above, because, while its volume is decreased,the lubricating oil and a gas are discharged from the exhaust passage.

In such manner, even when the vane passes the communicating hole afterit passed the exhaust passage, a differential pressure between the spacehaving a negative pressure due to an increase of the volume and thespace having a higher pressure than the relevant space is alsogenerated, thereby the lubricating oil in the space having a higherpressure is spouted into the space having a negative pressure through agap between the vane and the pump room.

At this time, the lubricating oil spouted into the space having anegative pressure is spouted in the direction opposite to the rotationaldirection of the vane, so that the lubricating oil positively impact onthe vane which subsequently passes the communicating hole.

As the result, the spouted lubricating oil seals the gap between thevane and the pump room, accordingly the vane pump can rapidly exert itsoriginal performance, even if the lubricating oil is not sufficientlyfed into the pump room.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, an embodiment shown will be described hereinafter. FIGS. 1 to 3show a vane pump 1 of this embodiment. This vane pump 1 is fixed on theside surface of an engine of an automobile not shown, and adapted togenerate a negative pressure in a booster of a brake control system notshown.

This vane pump 1 includes: a housing 2 having an approximately circularpump room 2A formed therein; a rotor 3 rotated at an eccentric positionrelative to the center of the pump room 2A by a driving force of theengine; a hollow vane 4 rotated by the rotor 3, for dividing the pumproom 2A into a plurality of spaces full-time; and a cover 5 for coveringthe pump room 2A.

In the housing 2, an intake passage 6 located above the pump room 2A, incommunication with the booster of the brake control system, for suckingin a gas from the booster, and an exhaust passage 7 located below thepump room 2A, for discharging the gas sucked in from the booster and alubricating oil fed from an oil supply groove 13 described below areprovided, respectively. Then, in the intake passage 6, a check valve 8is provided to hold a negative pressure in the booster, especially atstop of the engine.

Describing with reference to FIG. 1, the rotor 3 includes a cylindricalrotor portion 3A rotating in the pump room 2A, an outer surface of therotor portion 3A contacts with an inner wall surface of the pump room2A, and further, oppositely across a center line L drawn between thecenter of the rotor portion 3A and the center of the pump room 2A, theintake passage 6 and the exhaust passage 7 are disposed.

In FIG. 1, the rotor 3 is arranged to rotate counterclockwise shown, inthe following description, an upstream side in the rotational directionmeans a space adjacent to a clockwise side from a line drawn between thecenter of rotation of the rotor 3 and an arbitrary point of the pumproom 2A, and a downstream side in the rotational direction means a spaceadjacent to a counterclockwise side from the line.

Further, in a central portion of the rotor portion 3A, a hollow portion3 a and a groove 9 in the diametrical direction are provided, and thevane 4 is adapted to move slidably along in the groove 9 in thedirection perpendicular to the axial direction of the rotor 3.

Moreover, on both ends of the vane 4, caps 10 of which fore ends areformed to be semicircular are provided, and the fore end of this cap 10slides in contact with the inner wall surface of the pump room 2A and aslight gap is present between the vane 4 and the cap 10.

To the pump room 2A, the lubricating oil is arranged to be fed throughan oil supply groove 13, and a communicating hole of the oil supplygroove 13 is formed on the downstream side in the rotational directionof the vane 4 from a position at which the exhaust passage 7 is formed.

Therefore, the vane 4 is arranged to pass the oil supply groove 13 afterpassing the exhaust passage 7, so that the lubricating oil fed from theoil supply groove 13 is not discharged, just as it is, from the exhaustpassage 7.

In addition, in FIG. 1, the vane 4 is shown as oriented in the verticaldirection, hereinafter for illustrative purposes, a space situated onthe right side shown of the vane 4 and above the rotor portion 3A in thepump room 2A is called the “first space A”, a space situated on the leftside of the vane 4 is called the “second space B” and a space situatedon the right side of the vane 4 and below the rotor portion 3A is calledthe “third space C”.

FIG. 2 shows a cross-sectional view taken along the line II-II insituations shown in FIG. 1. In the housing 2, a bearing 2B adjacent tothe pump room 2A for supporting the rotor 3 is formed, and the cover 5is provided on the opposite side to the bearing 2B.

Next, the rotor 3 includes a shank 3B supported by the bearing 2B, fordriving rotationally the rotor portion 3A, and the shank 3B projectsfrom the bearing 2B to the right side shown, being linked to a coupling11 driven rotationally by a camshaft of the engine.

Then, end surfaces of the rotor portion 3A and the vane 4 on the leftside shown slide in contact with the cover 5, and further an end surfaceof the vane 4 on the right side rotates slidably in contact with aninner surface of the pump room 2A on the side of the bearing 2B.

Moreover, a bottom surface 9 a of the groove 9 formed in the rotor 3 isformed on the side of the shank 3B slightly from a surface on which thevane 4 and the pump room 2A slide, and a gap between the vane 4 and thebottom surface 9 a is present.

Then, in the shank 3B, in its central portion, an oil passage 12 forcirculating the lubricating oil from the engine and constituting an oilsupply passage is formed, and this oil passage 12 branches at apredetermined position in the same direction as the groove 9 andincludes a branch passage 12 a open into an outer surface of the shank3B.

Further, in the bearing 2B, an oil supply groove 13 formed in the axialdirection of the bearing 2B, for constituting the oil supply passageforming the communicating hole into the pump room 2A is formed, and asshown in FIG. 1, a width of the oil supply groove 13 along therotational direction of the vane 4 is formed to be not smaller than thatof the vane 4.

Owing to such configuration, when the branch passage 12 a coincides withthe oil supply groove 13 due to rotation of the rotor 3, the lubricatingoil from the oil passage 12 flows into the pump room 2A through the oilsupply groove 13, and approximately half of the lubricating oil isarranged to flow into the hollow portion 3 a of the rotor 3 from the gapbetween the vane 4 and the bottom surface 9 a of the groove 9.

Further, the rest of the lubricating oil is arranged to be sucked downinto the pump room 2A of which pressure becomes negative due to rotationof the vane 4, being sprayed into the pump room 2A through the gapbetween the vane 4 and the bottom surface 9 a of the groove 9 or the gapbetween the vane 4 and the cap 10.

With the configuration described above, operation of the vane pump 1according to this embodiment will be described. The rotor 3 is rotatedcounterclockwise as shown in FIG. 1 by operation of the engine throughthe coupling 11, and then the vane 4 rotates while reciprocating in thegroove 9 of the rotor 3, and the space divided by the vane 4 in the pumproom 2A changes in volume depending on rotation of the rotor 3.

Specifically described, FIG. 3 shows a situation when the vane 4 ispassing the oil supply groove 13 due to rotation of the rotor 3.

Then, the first space A in FIG. 1 is located on the left side of thevane 4 in this figure (FIG. 3) due to rotation of the rotor 3, and thesecond space B in FIG. 1 is located on the right lower side of the vane4 and the rotor 3 in this figure (FIG. 3).

The first space A has an increased volume compared to that in FIG. 1,and further sucked in a gas from the booster through the intake passage6, accordingly a pressure in the first space A becomes negative.

On the one hand, a volume of the second space B is decreased compared tothat in FIG. 1, and also the lubricating oil along with a gas in thesecond space B is discharged from the exhaust passage 7, at this time,in order to force the lubricating oil in the exhaust passage 7 to beremoved, the gas in the second space B is compressed to have a higherpressure than the first space A.

In such manner, during change from FIG. 1 to FIG. 3, a differentialpressure between the first space A and the second space B is generated,as the result, the lubricating oil which could not be removed throughthe exhaust passage 7 by the vane 4 is sprayed into the first space Athrough the gap between the pump room 2A and the vane 4, and the gapbetween the vane 4 and the cap 10, respectively, due to the differentialpressure.

Further, in the situations in FIG. 3, the branch passage 12 a in the oilsupply passage and the groove 9 of the rotor 3 are placed in the samedirection, if the vane 4 and the oil supply groove 13 coincide with eachother in position as shown, at the same time, the branch passage 12 aand the oil supply groove 13 also coincide with each other.

In this manner, when the branch passage 12 a and the oil supply groove13 coincide with each other, approximately half of the lubricating oilfrom the oil supply groove 13 flows into the hollow portion 3 a of therotor 3 through the gap between the vane 4 and the bottom surface 9 a ofthe groove 9, and subsequently this lubricating oil goes up in a mannerof flowing along an inner surface of the rotor due to a centrifugalforce by the rotor 3, and seals the gap between the cover 5, the rotor 3and the vane 4.

On the other hand, as for the rest of the lubricating oil, because theoil supply groove 13 is formed on the downstream side shown, thelubricating oil from the oil supply groove 13 is made misty to bespouted into the first space A through a bottom portion of the rotorportion 3A downstream, due to a negative pressure in the first space A.

That is, in this embodiment, to the first space A, the lubricating oilis adapted to be fed at two steps in form of the lubricating oil sprayedfrom the second space B as described above and the lubricating oilsprayed from the bottom portion of the rotor portion 3A downstream.

Further, the lubricating oil spouted into the first space A through thegap between the bottom surface of the rotor portion 3A and the bottomsurface of the pump room 2A, the lubricating oil through the gap betweenthe vane 4, the groove 9 and the bottom surface 9 a, and the lubricatingoil through the gap between the vane 4 and the cap 10, each is spoutedin the direction opposite to the rotational direction of the vane 4.

Therefore, against the vane 4 which, subsequently, reaches the exhaustpassage 7 due to rotation of the rotor 3, the lubricating oil is blown,and the lubricating oil gets into the gap between the vane 4 and thepump room 2A, and the gap between the cap 10 and the pump room 2A.

In such a manner, by spouting the lubricating oil positively in thedirection opposite to the rotational direction of the vane 4, thelubricating oil can rapidly circulate around in the gap between the vane4 and the pump room 2A or the gap between the cap 10 and the pump room2A, when the lubricating oil is not sufficiently distributed in the vanepump 1, especially such as at start of an engine.

Then, the lubricating oil not only lubricates the inside of the vanepump 1, but plays a role of sealing, and by sealing the gap between thevane 4 and the pump room 2A etc. with the lubricating oil, for example,airtight between the second space B and the first space A can be held.

Therefore, even immediately after start of an engine, the vane pump 1can rapidly exert its original performance.

On the contrary, in a conventional vane pump, because the direction inwhich a lubricating oil flows in is a direction following rotation of avane, especially a gap between a cap and a pump room is not rapidlysealed, so that immediately after an engine gets started, the vane pumpcannot rapidly exert its original performance.

FIG. 4 shows this with the experimental result. In FIG. 4, an elapsedtime from engine start is shown in the horizontal axis, and an abilityto generate a negative pressure in a booster is shown in thelongitudinal axis, and it may be seen that the vane pump 1 having theconfiguration of this embodiment denoted by the solid line brings out apredetermined ability to generate a negative pressure more rapidlycompared to the vane pump having a conventional configuration denoted bythe broken line.

In addition, the oil supply groove 13 may be formed at a position on theside of the exhaust passage 7 relative to the center line L, but it isnoted that, if the oil supply groove 13 is positioned on the side toomuch upstream in the rotational direction of the vane 4, a negativepressure to be generated by increasing a volume of the pump room 2A isreduced due to inflow of the lubricating oil, accordingly suctionbecomes insufficient, thereby performance of the vane pump cannot befully provided.

Further, in this embodiment, the width of the oil supply groove 13 inthe rotational direction has been set slightly larger to be not smallerthan that of the vane 4, but it is noted that, here, if the width of theoil supply groove 13 in the rotational direction is set to be narrowerthan that of the vane 4, a time for feeding oil is shortened andlubrication cannot be sufficiently performed, and on the contrary, ifthe width of the oil supply groove 13 in the rotational direction is setto be too wide, an amount of the lubricating oil becomes too large andthe vane 4 bears a load, when the lubricating oil is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a vane pump 1 according to an embodiment;

FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1;

FIG. 3 is an elevation view of the vane pump 1 showing a situation thata vane 4 moves from FIG. 1; and

FIG. 4 is a view showing the experimental result.

DESCRIPTION OF SYMBOLS

-   1 vane pump-   2 housing-   2A pump room-   2B bearing-   3 rotor-   3A rotor portion-   3B shank-   4 vane-   7 exhaust passage-   9 groove-   12 oil passage-   12 a branch passage-   13 oil supply groove

1. A vane pump comprising: a housing having a pump room in which anapproximately circular, inner wall is formed; a rotor rotating at aneccentric position relative to the center of the pump room and slidingin contact with a part of the inner wall of the pump room; and a vanerotated by the rotor, for dividing the pump room into a plurality ofspaces full-time, wherein in the housing, among spaces divided by acenter line drawn between the center of the pump room and the center ofrotation of the rotor, an intake passage in one space and an exhaustpassage in the other space are formed, respectively, further, in therotor and the housing, an oil supply passage intermittentlycommunicating with the pump room owing to rotation of the rotor isformed, and a lubricating oil is intermittently fed through acommunicating hole of the oil supply passage formed in the pump room,characterized in that the communicating hole is formed in a space on theside of the exhaust passage from the center line in the pump room, andthe vane passes the communicating hole, at the same time, the oil supplypassage and the pump room are adapted to communicate with each other. 2.The vane pump according to claim 1, characterized in that thecommunicating hole is formed at the back side from a position at whichthe exhaust passage is formed, seen from an upstream side in therotational direction of the vane.
 3. The vane pump according to claim 1,characterized in that a width of the communicating hole in therotational direction of the vane is formed to be not smaller than thatof the vane.
 4. The vane pump according to claim 1, characterized inthat the rotor comprises a rotor portion for holding the vane and ashank for driving rotationally the rotor portion, in the housing, abearing for supporting the shank is formed, the oil supply passagecomprises an oil passage formed in the shank, open into a slidingsurface along the bearing, and an oil supply groove formed on an innersurface of the bearing in the axial direction, for forming thecommunicating hole in the pump room, and when the oil passage coincideswith the oil supply groove due to rotation of the rotor, a lubricatingoil is fed into the pump room.
 5. The vane pump according to claim 4,characterized in that the oil passage comprises a branch passagebranching at a required position on the shank in the diametricaldirection of the shank, and the vane passes the oil supply groove, atthe same time, the branch passage and the oil supply groove are adaptedto communicate with each other.
 6. The vane pump according to claim 4,characterized in that in the rotor, a groove for holding the vane sothat it can reciprocate is formed in the diametrical direction, and byforming a bottom surface of the groove on the side of the shank from asliding surface at which the vane slides on the housing, when the oilpassage communicates with the oil supply groove, the lubricating oil isarranged to flow into a gap between the bottom surface of the groove andthe vane.